Gas cylinder valve assembly

ABSTRACT

The gas valve assembly includes a housing with a bore and a main valve body and a main valve stem mounted therein. The valve body has a fluid passage fluidly connecting the inlet and one of a housing and valve body outlet with the valve stem mounting a valve seat and being movable for blocking fluid flow through the passage. In two embodiments, the housing is threadable to the neck portion of a vessel for the inlet opening to the vessel interior and the main valve body mounts a manual operated shut off valve extending within the valve body to selectively block fluid flow through the passage and an excess flow valve to block fluid flow through the passage when the flow to the outlet is greater than desired. The last two mentioned valves include a common piston in the fluid passage.

BACKGROUND OF THE INVENTION

This invention is for a valve assembly usable with cylinders or tanks or other type vessels containing gas under high pressure in liquid or gaseous form.

U.S. Pat. No. 5,458,151 to Wass discloses a solenoid control valve mountable to the collar of a gas cylinder with the solenoid being in the interior of a cylinder for operating a valve for controlling the flow of pressurized gas from the cylinder. In U.S. Pat. No. 6,041,762 to Sirosh et al, there is disclosed controls for controlling the supply of gas from a gas vessel which includes a module having a pressure regulator in the interior of the vessel, pressure and temperature sensors, a pressure relief device, a solenoid valve and a check valve.

In order to provide an improved assembly for controlling the flow of pressurized fluid out of a container for pressurized fluid, this invention has been made. The gas cylinder valve assembly of this invention is mountable to the neck of a vessel containing pressurized gas or liquid and can be used, for example, for controlling the flow of fuel gas, including natural gas, to the engine of a motor vehicle, controlling the flow of gas to fuel cells, controlling the flow of gases such as oxygen, hydrogen, nitrogen for various industrial uses and controlling the flow of liquid for various industrial uses.

SUMMARY OF THE INVENTION

The gas cylinder valve assembly of two embodiments includes a valve housing or manifold threadedly mounted to the neck of a cylinder (vessel) for pressurized gas to extend into the interior of the cylinder and has an inlet opening to the cylinder interior and to a main valve bore. A fitting (valve body) is threaded to the housing to extend into the housing bore. The valve body has a body bore that opens through the external end of the body and through a valving surface remote from the external end. A valve stem mounts a valve seat that is seatable against the valving surface and mounts actuating mechanism for moving the valve stem to a main valve open position. The valve body bore has an excess flow piston therein that is resiliently retained in an open position to permit fluid flowing therethrough to a housing outlet. One end portion of the body bore has a bonnet therein which mounts an excess flow valve member and a manual shut off valve that is manually operable for abutting against the excess flow piston to selectively block fluid flow from the housing inlet to the housing outlet. In one embodiment the main valve stem is movable by magnet mechanism to main valve closed position while in a second embodiment a fluid pressure operated actuator moves the main valve stem to its open position and in a third embodiment the housing is mounted between a source of fluid under high pressure and apparatus to which the fluid is supplied with it including a main body portion extending into a valve seat the same as the other two embodiments.

An object of this invention is to provide a new and novel valve assembly for controlling the flow of pressurized fluid from the interior of a cylinder (vessel) containing fluid under high pressure. In furtherance of the above object, it is another object of this invention to provide the valve assembly with the force acting on the stem is based on the inlet pressure and is constant regardless of the outlet pressure. Another object of this invention is to provide new and novel valve apparatus that is not only operable for controlling the flow of pressurized fluid from a cylinder or tank but also to automatically block such flow in the event there is excess flow through the valve assembly outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross sectional view of the first embodiment of gas cylinder valve assembly of the first embodiment of the invention with only part of the gas cylinder being shown; said view being generally taken along the line and in the direction of the arrows 1-1 of FIG. 4;

FIG. 2 is an enlarged showing of a fragmentary portion of the apparatus shown in FIG. 1:

FIG. 3 is a further enlarged showing of a fragmentary portion of the apparatus of FIG. 1;

FIG. 4 is a fragmentary cross section that is taken along the line and in the direction of the arrows 4-4 of FIG. 1;

FIG. 5 is a longitudinal cross sectional view of the second embodiment of the invention; and

FIG. 6 is a longitudinal cross sectional view of the third embodiment

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-4 of the drawings, the gas cylinder valve assembly of the first embodiment of this invention includes a housing H having a lower, externally threaded portion 11 that is threadable to the internally portion of the neck 12A of the cylinder (tank or vessel) 12 to extend therein. The housing has a portion 13 external of the cylinder and has an axially elongated main bore B extending transversely therethrough, the central axis of the bore being designated C-C. The main bore has fitting (valve body) F mounted therein which has a first transverse end portion 14 threaded to the threaded first end portion 15 of the main bore.

Joined to the fitting threaded portion is an axially intermediate portion 17 that is of a smaller diameter than the fitting threaded portion and mounts axially spaced fluid seal members 18 forming a fluid seal between the fitting and the radial adjacent parts of the main bore portion 19 which is of a smaller diameter than the bore threaded portion. The bore portion 19 at its axial opposite end opens to a further reduced diameter portion 20 to provide an annular shoulder 21. Bore portion 20 in turn opens to a still further reduced diameter bore portion 22 which in turn opens to an enlarged diametric bore portion 23 that opens through the housing surface opposite the threaded main bore portion.

The main valve body has a cylindrical portion 27 joined to body portion 17 axially opposite the fitting threaded portion to provide an annular shoulder 15, portion 27 being of a substantially smaller diameter than each of bore portion 19 and fitting portion 17. Integrally joined to the opposite axial end of the cylindrical portion 27 is the major base of the frustoconical portion (valve element) 30 while its minor base is joined to body terminal cylindrical end portion 31. The valve element 30 includes a valving surface 30A. A fluid seal 32 is mounted to the cylindrical end portion 31 which extends into and is in fluid sealing relationship with annular main valve seat 33.

The valve seat 33, which may be made of plastic, is of a constant inner diameter except at the juncture to the minor base of a frustoconical tapered surface 33A. The valve seat 33 is mounted, for example press fitted, in the enlarged diameter bore portion 34A of the valve stem bore 34, the bore 34 extending axially through the main valve stem P. The stem bore includes a reduced diameter bore portion 34B to vent the space between the stem shoulder 38 and the valve body reduced diameter portion 31. Instead of having threads, the bore portion 34A and valve seat are provided with oppositely facing shoulders 24 that retain the valve seat in the bore portion 34A. The bore portion 34A is provided in the enlarged diameter end portion 33 of the main valve stem P. The valve stem bore reduced diameter bore portion 34B opens to the axial end of the valve stem axially opposite the enlarged diametric portion 35 and to bore portion 34A to provide the annular shoulder 38 against which the valve seat abuts. Bore portion 34B opens through the end of the main valve stem that is axially opposite the main valve body. A fluid seal (O-ring) 39 is mounted by the valve seat adjacent to the shoulder 38 to form a fluid seal between the outer periphery of the valve seat 33 and the inner peripheral wall that forms valve stem bore portion 34A.

The valve stem includes a reduced diameter, cylindrical portion 40 axially between and joined to its the threaded terminal end portion 41 and a larger diameter portion 42 which in turn is joined to the valve stem portion 35. The juncture of portions 40, 42 provide an annular shoulder 37. A fluid seal (O-ring) 44 is mounted on stem portion 40 to form a fluid seal between it and the housing wall surface defining bore portion 20.

A first disk 45 is threaded to the valve stem threaded portion 41 and is located in the housing bore portion 23 for axial reciprocal movement to reciprocally move the main valve stem and is prevented from rotating, for example by a key 45A mounted to the housing. The valve stem is of an axial length that when the main valve is in a closed position, valve element surface 33A abuts against the tapered surface 30A of the valve seat 30 to block fluid flow through the main valve, the terminal annular edge 33B of the valve seat 33 and the enlarged diameter portion terminal annular edge 35B are axially spaced from shoulder 15 to provide a fluid chamber 47 while the first disk is axially spaced from the shoulder 48 formed by the juncture of bore portions 22, 23 and the shoulder 53 of the stem enlarged diametric portion 33 at the juncture of stem portions 35, 42 are axially spaced from shoulder 21 to permit the valve stem moving to a main valve open position.

A cap (bonnet) 50 is threaded to the housing to closed the main bore portion 23 and has a bore 51 extending therethrough with an enlarged bore portion 51B opening to the main valve bore portion 23 to provide an actuator chamber in which a second disk 52 is mounted for rotation. The shaft 54A of a rotary solenoid 54 extends through the reduced diameter bore portion 51A of the cap and mounts the second disk for rotation therewith, the solenoid being mounted to the cap. Suitable controls 58 are provided for energizing and deenergizing the rotary solenoid in accordance with the demands of the apparatus 101 to which the pressurized gas is to be supplied.

The disks 45, 52 each mount permanent magnets 55, 56 which respectively are of opposite polarities with the magnets being the same radial spacing from the axis of rotation of the solenoid shaft and the same angular spacing from the angularly adjacent magnet that is of the opposite polarity. The axis of rotation of the solenoid shaft is coextensive with the central axis C-C of the main bore. In one rotary position of the solenoid shaft, the magnets on disk 52 are axially aligned with the magnets of the same polarity on disk 45 to be repelled by the magnets on disk 52 whereby the valve stem is moved to or remains in a main valve closed position and when the rotary solenoid is actuated, the disk 52 is rotated to a second position that the polarity of its magnets are aligned with magnets of opposite polarity on the reciprocal disk whereby the disk 45 is axialsly move toward the rotary disk for moving the valve stem to the main valve open position. When the main valve is in its open position, the rotary solenoid may be actuated to rotate the rotary disk sufficiently that the magnets of one polarity on the disk 52 are axially aligned with magnets of the same polarity on disk 45 for closing the main valve. Although in FIG. 4, the disk 52 is shown mounting four permanent with the magnet of one polarity being angularly offset from magnets of the opposite polarity, each disk may mount more or fewer magnets, depending the degree the disk 52 is to be rotated whereby the main valve stem moves between its valve open and closed positions. With four magnets such as shown in FIG. 4, the rotary shaft is rotated on 90 degrees for moving the main valve stem between its positions. A vent passage 102 opens to bore portion 23 and to the ambient atmosphere.

The outer periphery of the main valve cylindrical stem portion 35 is of a sufficiently smaller outer diameter than the diameter of the housing wall portion defining cylindrical bore portion 19 to provide an annular clearance space 49 that is in constant fluid communication with the fluid chamber 47 and the clearance space 43 that is axially between the shoulder 21 and the annular shoulder 53. The housing has a fluid passage (inlet) 70 that opens to the cylinder interior when mounted on the cylinder and to the annular clearance space 49 axially intermediate the shoulder 53 and the axial opposite edge 35B of the enlarged diametric portion 35. Thus, the shoulders 37, 53 are axially opposite the enlarged diametric portion from its annular edge 35B face in the axial opposite direction and are always subject to the inlet pressure acting to move the main valve stem to its closed position and acting on the enlarged diameter stem portion surface 35B and surface portion 33B of the valve seat 33 to move the main valve stem to its valve open position. Since the outer peripheral surface of the stem portion 40 is a little less than the minimum inner diameter of valve seat 33, the main valve stem is always urged by the inlet pressure to a valve closed position. As a result, the force required to move the main valve stem to a valve open position is many times less than the inlet fluid pressure.

The reduced diameter portion of main valve body F has a radial outer annular groove 72 that in a main valve closed position with the valve seat tapered surface 33A abutting against valving surface 30A opens radially just to the inner peripheral cylindrical surface of the main valve seat 33 and through cross bores 73 to the axially elongated valve body bore T which at its axial opposite end opens through the main body exterior end surface 75 that is axially opposite stem portion 31. The annular groove 72 is axially intermediate the terminal end surface of the valve seat 30 and the axial end surface 75, the body bore including bore a portion 77 that opens to a larger diameter bore portion 79 to provide an annular shoulder 78 that faces the end surface 75. Bore portion 79 in turn opens to a still larger diameter bore portion 80 which in turn opens to a larger diameter bore portion 82 to provide an annular shoulder.81. The bore portion 82 opens to bore portion 83 which in part is threaded to have a bonnet 84 threaded therein.

The bonnet 84 mounts the threaded end portion 85A of a manual shut off valve stem 85 of a manual shut off valve V while the reduced diameter portion 85B of the valve stem extends axially through a retainer washer 87 and into an annular valve member 88 of an excess flow valve E. The outer end of portion 85 may be provided with a screw driver slot 85c or a key way (not shown) or extend outwardly beyond end surface 75 to have a handle (not shown) mounted thereon to facilitate manually turning the valve stem 85 between the shut off valve open and closed positions. The reduced diameter valve stem portion 85B which is joined to threaded portion 85A mounts a shut off valve seat 90 that in a shut off valve closed position abuts against the axially adjacent annular end of the piston 91 to block fluid flow through the piston to the clearance space 94.

The valve member 88 at one end abuts against retainer washer 87, at the axial opposite end against the shoulder 81 and extends within the bonnet 84. Valve member 88 has a radial inner, tapered surface 88A providing a valving surface. An axially elongated annular piston 91 extends within stem bore portions 79, 80 which, in an excess flow open position, at one end 91E abuts against the shoulder 78 and at the opposite end abuts against a spring 92 which resiliently urges the piston in an excess flow valve open position. The spring extends within the valve member 88 and mounted thereby. The piston mounts a fluid seal 93 to provide a fluid seal with the inner peripheral wall defining bore portion 79.

The outer peripheral surface of the piston and bore portion 80 provide an annular clearance space 94 that opens to the tapered surface 88A of the valve member 88. The housing has an outlet 95 which opens to an annular groove 97 in the valve body F which through cross bores 98 fluidly connects the groove to the clearance space 94. The outlet is connectable by a line 100 to conventional apparatus 101 to which fluid from the cylinder is to be supplied. An excess flow valve E which blocks fluid flow from the housing inlet and through the assembly passage to the housing outlet when there is excess flow through the outlet includes at least parts of the piston 91 and the valve member 88, for example if there is a break in the line 100 or a problem with the apparatus leaking fluid at an excessive rate while the annular terminal surface end portion of the piston and the valve seat 90 which is seatable thereagainst forms part of the manual shut off valve

The piston has a bore 99 extending axially there through to, at one end, open to body bore portion 77 and at the opposite to the interior of valve member 88. The piston has a reduced outer diameter end portion 91A that is of a smaller outer diameter than the inner diameter of the valve member 88 to extend or be extendable therein. The end portion 91A is joined by a shoulder to the minor base of a piston frustoconical portion 91B which is abuttable against the valve seat 88A of the valve member 88 to block fluid flow from the piston bore to the clearance space 94. The inner diameter of the orifice 99B at the end portion 91A of the piston bore that is adjacent to the valve member 88 is less than that of the axially elongated piston bore portion 99C which opens to the main valve body bore portion 77.

When the main valve is in an open position, the spring 92 provides sufficient spring force that the piston is retained in abutting relationship to the shoulder 78. However, if there is a break in the line 100 or a problem develops in the apparatus 100 so that there is an excess fluid flow, the fluid flowing through the orifice develops a sufficiently great pressure drop that the spring force is overcome whereby the piston moves away from shoulder 78 to have the piston tapered shoulder 91B abut against the valve seat 88B to block fluid flow from the housing inlet to the housing outlet. With the piston moving away from the valve seat, fluid pressure acting between the piston annular end surface 91E and the shoulder 78 retains the piston in an excess flow valve in a closed position until either fluid under sufficient pressure is applied at the housing outlet or the manual shut off valve is operated to a closed position to push the piston to its excess flow valve open position whereby the spring again retains the piston in its valve open position. With to applying fluid pressure at the outlet to move the piston to a valve open position, the taper of the surfaces 91B and 88A are at different angles whereby a sufficient area of the surface 91B in the excess flow valve closed position is exposed to pressure applied to the outlet will move the piston to an excess flow valve open position. The excess flow valve provides an automatically operated safety feature to prevent undesirable escape of the pressurized fluid into areas where it is not desired.

When the main valve is in a closed position and the excess flow valve and the manually operated valves are in their open positions, the main valve blocks fluid flow through the fluid flow path from the cylinder 12 through the inlet, chamber 47, the clearance space 49 to the annular groove 72 and the cross bores 73 to the main body bore T and through the piston to the clearance space 94 and bores 98 to the housing outlet. Since in the main valve closed position, the cross bores 73 open to the cylindrical inner peripheral wall of the valve seat, the outlet pressure does not provide a force acting to move the main valve stem to a valve open position.

Referring to FIG. 5, the second embodiment of the invention, generally designated 110, is the same as the first embodiment other for the differences set forth herein. The second embodiment includes a housing R that is the same as housing H except that instead of a vent passage opening to bore portion 23, the housing R has a passage 111 that opens to bore portion 23 for selectively applying a pressurized fluid, for example air, from a source 111A. Further the second embodiment includes a main valve body, a manually shut off valve and an excess flow valve that is the same as the corresponding members of the first embodiment. The main valve stem, generally designated 117, of the second embodiment are the same as the first embodiment other than the valve stem portion 118 which is joined to stem portion 40. The stem 117 has a vent passage that functions the same as passage 34A. Instead of providing magnet mounting disks, an actuating piston 119 is mounted of stem portion 118 to abut against the shoulder formed at the juncture of stem portions 118 and 40 while retainer nuts 120 are mounted on the threaded part of stem portion 118 to abut against the piston. The piston has a radial inner groove mounting a fluid seal 121 in fluid sealing relationship with the stem portion 118 and a radial outer annular groove mounting a fluid seal 122 in fluid sealing relationship with the inner peripheral wall of bore portion 23. A cap 124 is threaded to the part of the housing having bore portion 23 to close the bore portion 23 and has a bore 127 extending axially therethrough. A spring 128 is mounted in the cap bore to abut against a cap shoulder and the piston 119 to constantly resiliently urge to the piston to move the main valve stem to its main valve closed position. When air under pressure is applied to passage 111 from a pressurized fluid source 112, the piston is moved from its main valve closed position to a valve open position. It is noted that the pressure required to move the actuating piston from its valve closed position to its open position is many time lower than the pressure applied from the cylinder 12.

Referring to FIG. 6, the third embodiment has a housing 150 having an axial bore 151 extending axially therethrough, the housing bore having a first end portion and a cap 124 closing the first end portion that is the same as that of the second embodiment. Further the valve stem, the valve seat mounted by the valve stem and the actuator mechanism for moving the valve stem is the same as that of the second embodiment. The housing bore has a threaded portion 151A that is threaded to have the valve body Y extend therein and has a threaded portion 152 threaded to the housing bore threaded bore portion. The main body Y includes an intermediate diameter portion 153 joined to thread portion 152 and is joined to a still smaller diameter portion 154 to provide an annular shoulder 155 axially spaced from the valve stem enlarged diameter terminal edge 35B and the main valve seat terminal edge portion 33B to provide an annular chamber 158. The main body includes a reduced diameter terminal end portion 159 axially opposite the valve body threaded end portion that is the same as the valve body reduced diameter portion 31 of the first embodiment and extends within the valve seat 33 in the same way.

The stem of the third embodiment has shoulders 53, 37 facing stem shoulder 170, 171 that are the same as shoulder 37. 21 with shoulder 170, 53 provide an annular clearance space 43 while the outer diameter of the cylindrical enlarged diametric portion to in combination with the body wall forming the body cylindrical bore 153 provides an annular clearance space 192 that opens to the housing inlet 181 and to the chamber 158 and the clearance space 43 and shoulder 37 in both of the main valve open and closed positions. The inlet is fluidly connected to a vessel 195 containing fluid under high pressure. The stem mounts a piston 119 with a spring 128 abutting against the piston and the cap 124 that are the same as the corresponding members of the second embodiment and a vent passageway 193 that is the same as that of the second embodiment.

The main body Y has an annular groove that opens radial to the annular inner peripheral surface of the valve seat with cross bores 73 opening thereto and to the axially elongated body bore 177 in the same manner as that of the first embodiment. The body bore 177 opens to the outlet 178 that opens outward of the body threaded portion which is fluidly connected to the conventional apparatus 180 to which fluid is to be supplied. 

1. A valve assembly for controlling the flow of fluid from a source under high pressure, comprising a housing having an inlet for fluid from the source and a main bore having a central axis and extending axially therethrough that opens to the inlet, a main valve stem mounted to the housing and extending within the housing bore, the valve stem having an enlarged diametric end portion that has an annular terminal edge within the housing bore and an axial stem bore opening through the annular terminal edge, an annular valve seat mounted in the stem bore and having an annular terminal edge portion and a generally cylindrical inner peripheral surface, an axial extedgeing main valve body mounted in the body bore, at least one of the housing and the valve body having a fluid outlet, the valve body having a reduced diameter first edge portion extedgeing within the valve seat, a valving surface portion joined to the body reduced diameter portion, a terminal second edge portion axially remote from the body first edge portion and a fluid passage opening through the body first edge portion to the valve seat inner peripheral surface and to the outlet, the valve body having a cylindrical portion in fluid sealing relationship with the housing and having a first shoulder facing the valve seat terminal edge portion and the stem enlarged diametric portion terminal edge to provide an annular chamber that opens to the housing inlet, the valve stem being axially movable between a valve closed position that the valve seat blocks fluid flow from the chamber to the opening of the passage to the valve seat and a valve open position permitting fluid flow from the chamber to the passage, the valve stem having at least one annular shoulder facing axial opposite the seat terminal edge portion and the enlarged diametric portion terminal edge in fluid communication with the inlet and of an area slightly greater than the seat terminal edge portion and the enlarged diametric portion terminal edge whereby the inlet pressure is in fluid communication with the at least one shoulder and the seat terminal edge portion and the enlarged diameter portion edge portion to constantly urges the valve stem to move to its closed position and power operated actuator for selectively moving the valve stem to its valve open position.
 2. The valve assembly of claim 1 wherein the housing has an end portion axially opposite the valve body to have the housing bore open therethrough, the valve stem has a second terminal end portion axially opposite the enlarged diametric portion, and the actuator includes a piston mounted to the valve stem second end portion for being moved by fluid pressure to move the valve stem to its valve open position.
 3. The valve assembly of claim 1 wherein the housing has an end portion axially opposite the valve body to have the housing bore open therethrough, a cap mounted to the last mentioned end portion with the body bore opening thereto, the valve stem has a second terminal end portion axially opposite the enlarged diametric portion, and the actuator includes a first disk mounted to the valve stem for only axial movement to move the valve stem between its positions, a second disk mounted in one of the cap and housing bores for rotary movement and a rotary solenoid connected to the second disk for selectively rotating the second disk, each of the disks mounting permanent magnets of opposite polarities with second disk in one rotated position having its magnets axially aligned with their polarities opposite those of the magnets on the first disk to move the valve stem to its valve open position and in a second rotated position, having its magnets axially aligned with magnets on the first disk of the same polarity for moving the valve stem to its valve closed position and a rotary solenoid for rotating the second disk.
 4. The valve assembly of claim 1 wherein the valve stem in both its valve open and closed positions has its terminal edge and the valve seat terminal edge portion axially spaced from the valve body shoulder to provide a fluid chamber, the enlarged diametric portion has a radial outer cylindrical surface, the housing bore has a cylindrical bore portion having the enlarged diametric portion extending therein and of a larger diameter than the enlarged diametric portion cylindrical surface to provide an annular clearance space that in both the valve stem open and closed positions opens to said chamber and is in fluid communication with the at least one shoulder and opens to the inlet.
 5. The valve assembly of claim 4 wherein the valve stem has a first reduced diameter portion joined to the enlarged diametric portion opposite its terminal edge and a second further reduced diameter portion joined to the first diametric portion axially opposite the enlarged diametric end portion to provide said at least one shoulder, the second diametric portion being in fluid sealing relationship with housing bore axially opposite the first reduced diameter end portion from the enlarged diametric portion and the valve body has a portion in fluid sealing relationship with the housing bore axially opposite the chamber from the valve seat.
 6. The valve assembly of claim 1 being mountable to a vessel having an interior for containing a fluid under high pressure wherein the housing has a portion mountable to the vessel with inlet opening to the vessel interior and an excess flow valve is mounted to the valve body in the passage between valve body first end portion and the outlet for automatically blocking fluid flow through the passage in the event the flow rate is above a preselected value.
 7. The gas valve assembly of claim 6 wherein the excess flow valve includes an annular piston that provides part of the passage and is axially movable in the valve body for having fluid flow therethrough and a manually operated shut off valve is mounted to the valve body that is selectively manually operable to in cooperation with the piston block fluid flow through the passage.
 8. The gas valve assembly of claim 7 wherein the valve body has a terminal end portion axially opposite the body reduced diameter portion and an axial bore that opens to the stem valve seat and to the body terminal end portion to at least in part form part of the passage, an annular valve member mounted in the body terminal end portion and having an annular valving surface opening toward the piston and in part defining the passage, the body bore having a first bore portion and a second bore portion of a reduced diameter that opens to the first bore portion to form an annular shoulder facing away from the valve stem intermediate the valve stem and the outlet, the piston being mounted in the first bore portion for axial movement between an excess flow valve open position abutting against the shoulder and an excess valve closed position axially spaced from the shoulder and abutting against the valve member valving surface to block fluid flow through the passage, the excess flow valve including a spring urging the piston to its excess flow valve open position and the piston having an orifice adjacent to the valve member valving surface to create a sufficient pressure drop to move the piston against the action of the spring to abut against the valve member valving surface to block fluid flow through the passage when there is excessive flow in the passage.
 9. A gas valve assembly mountable to the threaded neck of a vessel containing fluid under pressure, comprising a housing having portion threadable to the vessel neck portion, the last mentioned housing portion having an inlet opening to the vessel interior when the housing is mounted to the neck and an outlet, and a fluid passage fluidly connecting the inlet to the outlet, said passage including in the housing, an axially elongated housing bore having a central axis and extending axially though the housing and opening to both the inlet and the outlet, an operable main valve that forms at least part of the passage and extending in the housing bore for selectively blocking fluid flow through the passage and permitting fluid flow through said passage, a manually operated valve extending at least in part in said passage between the main valve and the outlet for selectively blocking fluid flow through the passage and an excess flow valve extending in the passage for automatically blocking fluid flow to the outlet in the event the rate of flow through to the outlet exceeds a preselected value, the excess flow valve being mounted by the main valve, and power operated actuator means for selectively operating the main valve between its position.
 10. The gas valve assembly of claim 9 wherein the main valve includes a main valve stem extending within the housing bore for axial movement between a main valve open position and a main valve closed position, the main valve stem including an enlarged diametric portion having an axial stem bore, an annular valve seat mounted in the enlarged diametric portion and an axially elongated main body extending within the housing bore that includes a reduced diameter end portion extending within the valve seat in both the main valve open and closed positions, an axially opposite end portion axially opposite the body reduced diameter end portion and a body bore opening to the valve seat adjacent to the reduced diameter end portion and to the body opposite end portion, the valve stem, the valve seat and the main body at least in part forming part of said passage.
 11. The gas valve assembly of claim 10 wherein the fluid passage includes a passage portion in the main body fluidly connecting the body bore to the outlet, the excess flow valve includes a piston axially movable in the body bore between an excess flow valve closed position and an excess flow valve open position, said piston having a piston bore extending axially therethrough that forms part of the passage portion intermediate the main valve reduced diameter portion and the outlet, and a valve member extending within the body bore, the piston and valve member having cooperating surfaces for abutting against one another to block fluid flow through said passage when there is excessive flow in the passage.
 12. The gas valve assembly of claim 10 wherein the body bore includes axial bore portions opening to one another to form an annular shoulder to limit the movement of the piston in an axial direction away from the valve member to the excess flow valve open position, the excess flow valve includes a spring acting between the valve member and the piston to resiliently urge the piston toward the body bore annular shoulder and the piston includes an end portion adjacent to the valve member and having an orifice to provide a drop of fluid pressure to overcome the action of the spring and draw the piston to its excess flow valve closed position when there is excessive flow through the piston.
 13. The gas valve assembly of claim 12 wherein the manual shut off valve includes a valve stem and a valve seat mounted by the valve stem with the valve stem being manually movable between an open position and a closed position that the seat mounted thereby abuts against the piston end portion to block fluid flow though the passage.
 14. The gas valve assembly of claim 12 wherein the valve seat has an inner peripheral cylindrical surface, the passage is in part formed by the valve body reduced diameter end portion having a radially annular groove that opens radially to the seat cylindrical surface and a cross bore opening to the body bore to provide the opening of the body bore to the valve seat.
 15. A gas valve assembly mountable to the threaded neck of a vessel containing fluid under pressure, comprising a housing having portion threadable to the vessel neck portion and an axially elongated bore extending axially therethrough, the housing bore having a first end portion and a second end portion, the last mentioned housing portion having an inlet opening to the housing bore and to the vessel interior when the housing is mounted to the neck and an outlet, an axially extending main body mounted in the main bore first end portion, a main valve stem mounted to the housing for axial movement between a main valve open position and a main valve closed position, said valve stem extending within the housing bore second end portion and having an enlarged diametric end portion that has a terminal annular edge axially adjacent to the main body, the enlarged diameter cylindrical end portion having an axial bore, an annular main valve seat mounted in the enlarged diameter end portion and having an axial bore that has an inner peripheral surface, the main body including a reduced diameter portion having an annular groove opening radially to the valve seat inner peripheral surface, an axial intermediate portion in fluid sealing relationship with the housing, a second end portion axially opposite the reduced diameter end portion, a valving portion extending between the axial intermediate portion and the reduced diameter portion to provide an annular shoulder opening toward the main valve seat and axially spaced from the main valve seat and the enlarged diametric portion in the main valve closed position to provide an annular fluid chamber and in the valve stem closed position being abuttable against the main valve seat to block fluid flow from the chamber to the annular groove and an axial main body bore opening to the annular groove and to the outlet, the main valve stem having at least one annular shoulder opening axially opposite from said chamber, the housing bore having a bore portion surrounding the stem cylindrical portion to provide an annular clearance that that in both the valve stem open and closed position that has the inlet opening thereto, opens to the at least one annular shoulder and opens to said chamber.
 16. The gas valve assembly of claim 15 further characterized in that an excess flow valve is mounted in the body bore for blocking fluid flow through the main body bore to the outlet when the flow rate is above a desired rate, the body bore including a first body bore portion and a second bore portion of a smaller diameter than the first bore portion and opening thereto to provide a second annular shoulder facing away from the body reduced diameter portion, the excessive flow valve includes a piston mounted in the second bore portion for axial movement between an excess flow valve open position abutting against the second annular shoulder and an open position axially spaced from the second shoulder, the piston having a piston bore extending axially therethrough, an annular valve member mounted in the main body bore second end portion to have the piston abut thereagainst in the excess flow valve closed position to block fluid flow from the piston bore to the outlet.
 17. The gas valve assembly of claim 16 wherein the excessive flow valve includes a spring acting against the valve member to resiliently retain the piston in abutting relationship to the second shoulder and the piston has a first end portion abuttable against the second shoulder, a valve seat for abutting against the valve member, a second end portion extendable into the valve member in the excess valve closed position, the piston second end portion providing an orifice that when excessive fluid flows therethrough there is a pressure drop sufficiently great that the piston moves against the spring action to abut against the valve member.
 18. The gas valve assembly of claim 17 wherein the body bore includes a third bore portion of a larger diameter than the body second bore portion to provide an annular clearance between the wall portion defining the valve body bore and the piston to provide at least in part the opening of the valve body bore to the outlet and that opens to the piston bore in the excess flow valve open position. 